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Noise from dance floor?

Discussion in 'Live Sound [BG]' started by Toey, Dec 15, 2018.


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  1. Toey

    Toey

    Oct 16, 2013
    Hi, has anyone else had this problem. I was playing a gig last night in a function room with an 'star lit' dance floor (little LEDs embedded into it) but anytime I went near it my IEMs would howl and I'd get a mains 50hz hum from FOH. I got around it by keeping away from the dance floor but I'm wondering what I could do to stop it happening in future (what did other people do stop stop it happening?).

    Thanks.

    For info I use: Fender P special, markbass little mark 500 and markbass 2x10 traveller, Zoom b3 pedal, gear4music iem.
     
  2. Toey

    Toey

    Oct 16, 2013
    Btw ground lift on the pedal made things worse!
     
  3. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    Ft.Worth/Dallas
    1964 Audio artist, Fractal Audio Beta Tester
    My firsts guess is that it had nothing [specifically] to do with the embedded LED's. We run wired/wireless with LED lights on the stage quite frequently.. I also run FOH for bands doing same thing.
    My 2nd guess is that the lights were on a shared power source [very common in "function" and hotel ballrooms IME] - they were not grounded - and you got a ground loop working...
     
  4. Toey

    Toey

    Oct 16, 2013
    Thanks s0c9. I'm pretty sure we were playing out of just 3 sockets! So I think you are right. But how come when I pressed the ground lift it got worse (I don't doubt you, I want to understand a bit better).
     
  5. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    Ft.Worth/Dallas
    1964 Audio artist, Fractal Audio Beta Tester
    Which ground lift were you pressing?
    Assuming it's the one on the back of your markbass, then yes.. it CAN make it worse.
    You were probably running the console off one circuit and your bass off another, and they do NOT have a common ground, or no grounding at all. This will often introduce ground noise (mains hum) into the system.

    I used to have a similar issue at a major venue we played.. Turns out the stage boxes (embedded in the stage floor) were NOT grounded (even tho' 3-prong) and I ALWAYS had hum, made worse by lifting the ground on my amps DI signal to their stage box. I solved the problem by finding a grounded outlet about 30 feet away, and ran an 14-gauge extension cable to it. Problem solved.
     
    Last edited: Dec 15, 2018
  6. Toey

    Toey

    Oct 16, 2013
    Thanks. That sounds logical and quite probable seeing as the building was built in the 30s and rewired bit by bit.

    The ground lift was on the pedal.

    If I had plugged my amp into the same sockets as the mixing desk and dance floor is it possible that the issue might not have been there? Also if I had unplugged the mains power to pedal (ran off batteries), could that have got rid of the problem?
     
  7. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    Ft.Worth/Dallas
    1964 Audio artist, Fractal Audio Beta Tester
    I can't say for certain, but there's a chance that doing what you suggest would work. Best thing is to try it! :D
     
    Toey likes this.

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